the plan is to build the web app with react.js and also build the backend using express.js specfically using rest api to connec to mySQL database....the problem is
for authentication, my supervisor doesnt want me to store password anywhere, instead he suggested me to build an authentication using the usename and password that we use to connect to mySQL database. For example, when i try to make a connection with mysqlCreateConnection method, theres a section where i have to fill out the ip address and username and password. the problem is if i do this, when the user logs out, the connection between backend and database will disconnect......
is it possible to use mySQL createconnection in the front end? so whenever the user logs in it will connect to the database directly from the frontend? once the connection is created, then use backend rest api? if this works i assume the rest api has to be hosted with the same url as the frontend, since we made the connection to mySQL database in the frontend.......but again if we do this, doesnt it defeat the purpose of backend? meaning anyone can login to the frontend and change whatever they want to the backend?
so the result will be like
within the frontend. user logs in using mySQL workbench username and password, then that username and password is going to fill out the mysql createconnection method(this method is written in the frontend). which will then try to connect to the database.
user logs in successfull
user fills out a form about a product and clicks on submit and this data is send to our rest api, and mySQL database adds the data in.
here are examples of router-token and router-session within the app if you are at express.js.
db.js
const mysql = require("mysql2")
const config = require("../../config/config.json").DB
module.exports = mysql.createPool({
host: config.host,
user: config.username,
password: config.password,
database: config.database,
waitForConnections: true,
connectionLimit: 100,
queueLimit: 0,
multipleStatements: true
})
db.fun.js
const db = require("./db").promise()
let query = async(sql, data) => {
try {
let d = await db.query(sql, data);
return d[0];
} catch (err) {
console.log(`EDB: ./app/database/db.fun.js 8rows \n${err}`);
return { err: 1, errdata: err };
}
}
module.exports = {
query: query
}
import query
(async function(){
const { query } = require("../database/db.fun");
let user = await query("SELECT * FROM users",[]);
console.log(user)
})();
Related
I have a Node.js Stackblitz project that I am trying to connect to a remote MySQL database. It is not possible to have a MySQL database within Stackblitz, hence trying the remote approach. However I get "Error: connect ETIMEDOUT" whenever I attempt a connection. Any help or pointers much appreciated.
I am using the code below. The remote database is accessible with the credentials I am using and returning data when used outside of Stackblitz. Is remote database access not possible with Stackblitz or am I missing something?
const express = require('express');
const mysql = require('mysql2/promise');
const app = express();
const port = 3010;
const path = require('path');
app.use(express.static('static'));
app.get('/', async function (req, res) {
try {
// create connection
const connection = await mysql.createConnection({
host: process.env.DB_HOST,
port: process.env.DB_PORT,
database: process.env.DB_DATABASE,
user: process.env.DB_USER,
password: process.env.DB_PASSWORD,
});
// query database
const [rows, fields] = await connection.execute('SELECT * FROM `user`');
res.send({
rows,
fields,
});
} catch (err) {
console.log('err:', err);
}
});
app.listen(port, () => {
console.log(`Example app listening at http://localhost:${port}`);
});
For anyone looking for an explanation.
Currently a mysql database cannot reside in StackBlitz. Additionally, neither can it connect to an external mysql database on its own either.
You therefore required a backend API outside of StackBlitz to make the database calls, negating the reason for building the backend on StackBlitz in the first place (IMO). Therefore, the suggested setup currently would be a localhost backend API accessed from a frontend in StackBlitz via an ngrok secure address.
StackBlitz are working on getting basic server requests running in the future. So, watch this space.
I hope this answer helps save others time.
I'm using React Native. I want to find the data I entered in React Native in the database. For example, in the database of the user name I entered, "select id from table where ('data I entered in react native')". I want to find the table with the user name and pull the user's id.
var name = this.state.username;
"select id from table where (name)"
I want to pull the id of the user name like this.
There is no direct connection between RN and Mysql. Use Node js for this.
Step: 1
npm install express
npm install body-parser
npm install mysql
Step: 2
const connection = mysql.createPool({
host : 'localhost', // Your connection adress (localhost).
user : 'root', // Your database's username.
password : '', // Your database's password.
database : 'my_db' // Your database's name.
});
// Starting our app.
const app = express();
// Creating a GET route that returns data from the 'users' table.
app.get('/users', function (req, res) {
// Connecting to the database.
connection.getConnection(function (err, connection) {
// Executing the MySQL query (select all data from the 'users' table).
connection.query('SELECT * FROM users', function (error, results, fields) {
// If some error occurs, we throw an error.
if (error) throw error;
// Getting the 'response' from the database and sending it to our route. This is were the data is.
res.send(results)
});
});
});
// Starting our server.
app.listen(3000, () => {
console.log('Go to http://localhost:3000/users so you can see the data.');
});
Now, how do we get that data on our React Native App?
That's simple, we use the fetch function.
To do that, instead of using 'localhost:3000', you'll have to directly insert your PC's ip adress. If you use 'localhost', you're acessing your smartphone/emulator's localhost. And that's not what we want. Follow this example:
test(){
fetch('http://yourPCip:3000/users')
.then(response => response.json())
.then(users => console.warn(users))
}
You need to have a backend service/API in order to fetch data from database. try using Node, and write a simple backend since its JavaScript. You can execute sql queries on backend, retrive data from mySQL to your node server and then you can fetch data from the backend server to react-native using fetch method. (both your backend API and the device that running react native application should be running on the same network.)
In my NextJS Vercel app, I am unable to successfully connect to my remote MySQL database which is located on GoDaddy, after following Vercel's official tutorial.
I expect the api pages to return JSON data that resulted from the database query. Instead I am getting
I tried changing the username, but for some reason, the 4 environment variables that I have - MYSQL_USER, MYSQL_DATABASE, MYSQL_HOST, and MYSQL_PASSWORD - never update on the live site! I changed in Production, Preview, and even Development, and they stay the same in the above link’s object.
Everything works fine on my localhost because my home IP address is whitelisted in cPanel. But Vercel has dynamic IPs so I can't do this on the live site. It also works fine if I host on GoDaddy, but I need to host on Vercel.
Here’s my source code for the db.js file which connects to the database
lib/db.js
const mysql = require('serverless-mysql');
const db = mysql({
config: {
host: process.env.MYSQL_HOST,
database: process.env.MYSQL_DATABASE,
user: process.env.MYSQL_USER,
password: process.env.MYSQL_PASSWORD,
}
})
exports.query = async query => {
try {
const results = await db.query(query);
await db.end();
return results
} catch (error) {
return {
error
}
}
}
pages/api/columns/index.js
const db = require('../../../lib/db')
const escape = require('sql-template-strings')
/**
* Queries the database to return the newspaper's columns
* #param {IncomingMessage} _req The request object (unused)
* #param {ServerResponse} res The response object
*/
module.exports = async (_req, res) => {
const columns = await db.query(escape`SELECT * FROM columns ORDER BY id`);
res.status(200).json({ columns })
}
I expect this result, which appears locally:
Connecting to a remote database only works with Cloud hosting (e.g. Microsoft Azure, AWS). Because I am using a Hosting service, this won't work.
In Remote MySQL, whitelist %.%.%.%. Because Vercel's IPs are dynamic, this will allow a consistent connection between Vercel and the database. It is also a security risk, but I have a password protection.
I'm building an Node application which will query simple and more complex (multiple joins) queries. I'm looking for suggestions on how I should manage the mySQL connections.
I have the following elements:
server.js : Express
router1.js (fictive name) : Express Router middleware
router2.js (fictive name) : Express Router middleware
//this is router1
router.get('/', function (req, res){
connection.connect(function(Err){...});
connection.query('SELECT* FROM table WHERE id = "blah"', function(err,results,fields){
console.log(results);
});
...
connection.end();
})
Should I connect to mysql everytime '/router1/' is requested, like in this example, or it's better to leave one connection open one at start up? As: connection.connect(); outside of: router.get('/',function(req,res){
...
}); ?
I am using mysql2 for this, it is basicly mysql but with promises. If you use mysql you can also do this.
Create a seperate file called connection.js or something.
const mysql = require('mysql2');
const connection = mysql.createPool({
host: "localhost",
user: "",
password: "",
database: ""
// here you can set connection limits and so on
});
module.exports = connection;
Then it is probaly better you create some models and call these from within your controllers, within your router.get('/', (req, res) => {here});
A model would look like this:
const connection = require('../util/connection');
async function getAll() {
const sql = "SELECT * FROM tableName";
const [rows] = await connection.promise().query(sql);
return rows;
}
exports.getAll = getAll;
You can do this with or without promises, it doesn't matter.
Your connection to the pool is automatically released when the query is finished.
Then you should call getAll from your router or app.
I hope this helped, sorry if not.
Connection pooling is how it should be done. Opening a new connection for every request slows down the application and it can sooner or later become a bottleneck, as node does not automatically closes the connections unlike PHP. Thus connection pool ensures that a fixed number of connections are always available and it handles the closing of unnecessary connections as and when required.
This is how I start my express app using Sequelize. For Mongoose, it is more or less simlar except the library API.
const sequelize = new Sequelize('database', 'username', 'password', {
host: 'localhost',
dialect: 'mysql',
pool: {
max: 5,
min: 0,
acquire: 30000,
idle: 10000
}
});
sequelize.authenticate()
.then(
// On successfull connection, open a port
// and listen to requests. This is where the application
// starts listening to requests.
() => {
const server = http.createServer(app);
server.listen(port);
},
)
.catch(err => {
console.error('Unable to connect to the database:', err);
console.error('Cancelling app server launch');
});
The app is started only after a database connection has been established. This ensures that the server won't be active without any database connection. Connection pool will keep the connections open by default, and use a connection out of the pool for all queries.
If you use createPool mysql will manage opening and closing connections and you will have better performance. It doesn't matter if you use mysql or mysql2 or sequlize. use a separate file for createPool and export it. You can use it everywhere. Don't use classes and just do it functionally for better performance in nodejs.
> npm install mysql
mysql is a great module which makes working with MySQL very easy and it provides all the capabilities you might need.
Once you have mysql installed, all you have to do to connect to your database is
var mysql = require('mysql')
var conn = mysql.createConnection({
host: 'localhost',
user: 'username',
password: 'password',
database: 'database'
})
conn.connect(function(err) {
if (err) throw err
console.log('connected')
})
Now you are ready to begin writing and reading from your database.
ANy idea how can I connect from NodeJs to the Mysql ClearDB on Heroku?
I was able to connect to the ClearDB Mysql runing on Heroku from Navicat, I even created a table called t_users. But I'm having problems connecting from NodeJs from Heroku.
This is my code, it is very simple: everything works find until it tries to connect to MySQL
web.js:
var express = require("express");
var app = express();
app.use(express.logger());
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'us-cdbr-east-04.cleardb.com',
user : '',
password : '',
database : ''
});
connection.connect();
app.get('/', function(request, response) {
response.send('Hello World!!!! HOLA MUNDOOOOO!!!');
connection.query('SELECT 1 + 1 AS solution', function(err, rows, fields) {
if (err) throw err;
response.send('The solution is: ', rows[0].solution);
});
});
var port = process.env.PORT || 5000;
app.listen(port, function() {
console.log("Listening on " + port);
});
This is what I got when I run on the command line: Heroku config
C:\wamp\www\Nodejs_MySql_Heroku>heroku config
=== frozen-wave-8356 Config Vars
CLEARDB_DATABASE_URL: mysql://b32fa719432e40:87de815a#us-cdbr-east-04.cleardb.com/heroku_28437b49d76cc53?reconnect=true
PATH: bin:node_modules/.bin:/usr/local/bin:/usr/bin:/bin
This is the LOG:
http://d.pr/i/cExL
ANy idea how can I connect from NodeJs to the Mysql ClearDB on Heroku?
Thanks
Try this. Hope this will help you
mysql://b32fa719432e40:87de815a#us-cdbr-east-04.cleardb.com/heroku_28437b49d76cc53?reconnect=true
var connection = mysql.createConnection({
host : 'us-cdbr-east-04.cleardb.com',
user : 'b32fa719432e40',
password : '87de815a',
database : 'heroku_28437b49d76cc53'
});
Use this details and connect it in mySQL work bench, and import your localhost db
The base code was ok, I missed some NodeJS code.
I did a video explaining how to connect to MySqlusing NodeJS on a Heroku server, take a look:
http://www.youtube.com/watch?v=2OGHdii_42s
This is the code in case you want to see:
https://github.com/mescalito/MySql-NodeJS-Heroku
createConnections accepts config as well as connectionString.
export function createConnection(connectionUri: string | ConnectionConfig): Connection;
So below solution would work.
var connection = mysql.createConnection('mysql://b32fa719432e40:87de815a#us-cdbr-east-04.cleardb.com/heroku_28437b49d76cc53?reconnect=true);
or you can set the connection url in environment variable DATABASE_URL
var connection = mysql.createConnection(process.env.DATABASE_URL);
One should need to use pool connection for database connection to handle better mysql conncurrent request as follows
var pool = mysql.createPool({
connectionLimit : 100,
host : 'us-cdbr-iron-east-05.cleardb.net',
user : 'b5837b0f1d3d06',
password : '9d9ae3d5',
database : 'heroku_db89e2842543609',
debug : 'false'
});
It just because pool maintain the connection.release() on its own , so you do not have to bother where you should need to release the connection.
On the other hand you should need to provide user, password and database name as i mentioned in my code.
When u get provisioned from heroku then you get a cleardb database name.
on clicking clear db database button you will find username and password.
and to get database url you have to run the following commands in terminal as follows;
heroku login
heroku app -all (it shows the app list name )
heroku config --app appname (it will provide the database url).
Rest you would need to worry, just add all dependency into your package.json before pushing to heroku master.
After then you will have no problem on deploying nodejs application to heroku server.
Looking at the log timestamps, it seems like your connections are timing out. Either create a wrapper for 'getConnection' that checks the connection health and re-establishes if necessary, or try to use the mysql Connection Pool feature, which can do that for you.